The invention relates to a device for tracking the a target mark for a therapy apparatus which in particular serves as an ultrasound therapy apparatus, for example a lithotripter, for the destruction or treatment of objects in the inside of a human or animal body and which is coupled to a diagnosis apparatus, in particular an ultrasound diagnosis apparatus, which comprises an ultrasound transmitter/receiver head, for scanning the object, and which is coupled to a sound source, for example a pressure impulse source, of the ultrasound therapy apparatus, wherein the position of the transmitter/receiver head relative to the axis of symmetry of the sound source can be adjusted and wherein the scanning plane of the transmitter/receiver head goes through the focus of the sound source.
Such a device is known from DE 35 43 867 A1 (Richard Wolf GmbH). The known device serves for the location and destruction of concretions in bodily organs, such as for example kidney stones, and offers a simplified and inexpensive apparatus with regard the design of the structural components, and in which the body organ, the concretion located therein, as well as the destruction procedure may be acquired by the transmitter/receiver head of the ultrasound diagnosis apparatus and may be displayed on a monitor. Subsequently the known device is explained with reference to FIGS. 6 and 7 which schematically show a pressure impulse source or a shock wave transducer 1 in combination with a transmitter-receiver head of an ultrasound diagnosis apparatus.
The shock wave transducer 1 has the shape of a spherical calotte in which individual piezoelectric transducer elements, which are not further represented, are arranged and with their active beaming surface are directed on the focus 2.
With the device according to FIG. 6, the transmitter/receiver head 3 (B-scanner) of the diagnosis apparatus (not shown) is so fixed at the upper end of the holder 4 that the longitudinal axis 5 of the scanner and the axis of symmetry 6 of the shock wave transducer 1 coincide. The holder 4 runs through the centre of the transducer 1 which in a central region 1a does not comprise any transducer elements by which means the holder 4 and the scanner 3 will lie in a sound shadow having the peripheral shape of a cone 7, even when here the scanner or its holder externally protrudes relatively far out of the space enclosed by the spherical calotte shape of the transducer 1.
The outer contour of the shock wave field intersecting at the focus 2 is indicated by the cone 8. A concretion 102 for example in a kidney 101 of the patient 10, and on which the focus 2 in this case is already directed, is to lie in the section plane 9 acquired by the scanner 3 and lying in the plane of the drawing.
Moreover the holder 4 with the scanner 3 may be turned about the axis of symmetry 6 in the direction of the arrow A, this for example being with an angular range of 90.degree., so that the production of at least two correspondingly angularly displaced sectional pictures is possible. Furthermore the scanner 3 by way of axial movement of the holder 4 relative to the transducer 1 may be adjusted in the direction of the double arrow B, by which means an adaptation of the scanner position to the patient is possible. A further possible position of the holder 4 and of the section plane 9 is shown dashed in FIG. 6.
If the scanner 3 as with the device according to FIG. 6 projects relatively far into the usual sound field geometry of the transducer 1 and thus from the beginning has a correspondingly small distance to the concretion 102, then advantageously a commercially available and thus inexpensive, short focusing scanner may be applied. This advantage in general does not apply to a device according to the type of embodiment shown in FIG. 7, in which the scanner 3 is arranged in or directly bordering the space enclosed by the calotte shape of the transducer 1, and may not be axially adjusted. On the other hand it is advantageous with this embodiment that for the shielding of the scanner and its holder in the centre of the transducer calotte, only a relatively small surface of transducer elements must remain free.
Furthermore also with the device according to FIG. 7, the holder with the scanner 3 in the transducer center is rotatably mounted (arrow A) about the axis of symmetry 6. By way of this, as with the previously described example, the representation of several section planes 9 is possible. Although in FIG. 7 seven various section planes distributed about 360.degree. are drawn in, in practise the representation of for example two section planes displaced by 90.degree. is sufficient and with this an unproblematic location of the concretion is made possible. Furthermore with this device, on the one hand a relatively long focusing B-scanner becomes necessary, but on the other hand, also during the application with shock waves, an ultra-sound control via the scanner is possible since the scanner, after completion of the locating procedure and also during the operation of the transducer 1, may remain in its shown position and continuously produce B-pictures.
Moreover both devices according to FIGS. 6 and 7 fulfill the ideal requirements for locating and destroying body concretions, since the transducer 1 and the B-scanner 3 lie on the same axis 6 and since because of this, the same tissue layers are passed through, from the location sound field as well as from the shock wave sound field. Thus it is usually not possible for various interruptions, possibly caused by imaging errors, of the wave fronts of both sound fields to occur.
Ultrasound diagnosis apparatus and therapy apparatus are principally two apparatus applied for various purposes, which should also be operable independently of one another. This means that with a combination envisaged by this invention of such differing apparatus, it is desirable that various ultrasound diagnosis apparatus, in particular any commercially available ultrasound diagnosis apparatus may be coupled in combination with a therapy apparatus for example, without having to carry out complicated and costly adaptations of both these apparatus.